Headlight realys

[rjbaren]

With my recent success with the horn relay I would like to try to do the same with the headlights. 

1).  Do I need a separate power supply for each of the two relays? 

2). I have been unable to get a wire through the rear firewall to the battery but, is it possible to pass a wire or two through the opening where the heater control cable exits the chassis and run it (them) up to the battery from the console?

3).  Do I use a four prong relay and just do the low beams, or get a five prong relay for both low and high beam?

Sorry, but you can probably tell by these questions I am not well versed in electrical work.  Thank you in advance for your help.

[jbcollier]

1)  No, you can share the battery feed amongst a number of relays, including your recent horn relay.

2)  Can’t give you specifics on routing as I have an S1.  You need to run the wire in a protective sheath.  Given the length of the run, it would also have to be a thick wire.  12g at a minimum.

3)  You need two relays: one for the high beam and one for the low beam.  The relays would be triggered by the normal feed to the headlights.  Each relay would supply both the left and right headlights.

The headlight wiring has a main junction by the RH headlight.  There is a short harness that goes from the right side to the left.  By the RH headlight is the logical place to put the relays.

[EuropaTC]

I fitted relays to my car a while ago, in fact I actually fitted a second fuse box in the front compartment as well although you don't need one just for headlight relays.

I took the main power lead from the back of the ammeter, same gauge wiring as the other brown leads there. That feeds the second fuse box although in your case it could simply feed directly to the relays. I took the lead from the back of the dash underneath the front luggage compartment (where the handbrake and windscreen washer stuff goes) and on to the auxiliary fuse box/relays.

If you're unhappy taking from the ammeter then you could take a feed directly from the battery but it would need to be a hefty gauge as it's a long run. You could either feed through the chassis central tunnel but it would need to be firmly out of the way and well insulated against vibration/rubbing or alternatively through the cabin using the same holes that the existing loom does.  That's some dismantling and why I made up leads to go from the ammeter instead.

That's the hardest part. As John says the existing loom wiring for headlamp "on" goes to the relays, then you make up some more leads for earth/dip/main output from the relays. The diagram shows how mine goes together, I can take pictures later if that would be more helpful.

Brian

Edit to add photo showing the rat's nest of wiring in the front.  Power feed (Brown) comes from the ammeter through the existing access hole which the washer tubing goes through.  All relays have a common earth. I think (note think, it was some time ago  ) that I left the loom mostly un-touched and made up additional short sections in the correct colours for the relays.  Main/Dip/Rad. Fan are now individually fused (with a spare for when I get around to fitting that Flux Capacitor...)

[rjbaren]

Brian, thank you.  Your wiring diagram is exactly what I needed.  In my case I will stay with my single wire coming off the fuse box.  I have decided to add the second fuse box.  I will have the two headlight relays, the horn relay, and I will add the auxiliary fan relay.  For me, the trick will be figuring out where to insert the headlight relays.  I see I have two sets of bullet connectors for both the blue/red and blue/white in the front compartment, one pair on the left under the fan and one pair on the right near the rear floor of the compartment.  Once I figure that out I should be on my way.

If you do have some pictures they would be very helpful.     

[gideon]

Brian, I'm impressed that you have a wiring diagram for your car.  What software did you use to prepare it?  It would be helpful to have a way to take an existing Europa wiring diagram and edit it to match changes made for a particular car.

[EuropaTC]

Hi Gideon,

There's nothing magical about the wiring diagram I'm afraid, in fact it's not exactly accurate because I've got a pertronix in the distributor, essentially the same wiring but not shown there.

I scanned the original at 300dpi and used Photoshop to tidy it up and add the new bits in. It's quite easy to do, by creating layers you can get the layout exactly the same so the original scan just becomes a template. As I say, it's not difficult, just time consuming. You can get software to do circuits but I reckoned it was just easier to scan the manual and tidy it up.

I printed and laminated it at just under A3 size, which fits nicely under front & rear lids using double sided sticky tape.  So I have a wiring diagram at both ends which helps my memory !

Brian

[rjbaren]

Ray from R.D. Enterprises recommended a company called British Wiring.  I plan to purchase some wire for the relays in the proper colors and I am wondering what gauge wiring to buy?  They sell 14 strand 18 gauge and 28 strand 14 gauge wire.  This would be in case I need to add or replace the wires to the headlights, radiator fan and horn.  The supply wires to the fuse box and relays I plan to use 12 gauge wire.

[jbcollier]

14G is what you want for supplying each light, horn, fan, etc with power and ground.  18G is what you use for signal/trigger/ground wires for the relay coils.

[Gmg31]

Saw this on another site very neat and tidy and not difficult to make

[Gmg31]

This item is very on Amazon. Cheap and cheerful

[SilverBeast]

I've got one of those from Ebay and a 6 relay version.  I'll be using a relay each for dipped and main on headlights (4 total, I intend to go to H4 halogen) , one for cooling fan (as I have an aluminium radiator to fit at the he same time) and one for air horn.

[rjbaren]

I have a couple of follow-up questions. 

I have found four bullet connectors in the front radiator compartment.  There is a pair on the left with a Blue/White for the low beams and a Blue/Red for the High beams.  There is an identical pair on the right.  They would be located under the washer bag and under the blower motor.  An easy place to take my feed(s) to the relays.  Could I double gang the Blue/White wires into the input of the low beam relay and likewise double gang the two Blue/Red wires into the input of the high beam relay?  The relays I have on order have two 87 terminals for two output wires, one for each right and left light, where I would use a 12 gauge wire to each respect headlight.

Lastly, when I had the radiator re-cored I had a metric nut braised where the fan switch bulb went.  I installed a threaded fan switch from an older BMW with a 100c degree on and a 95c degree off.  With this new switch, is it still necessary to have a relay for the radiator fan?  Currently, I do not have a switch on the dash, but I am thinking of piggy backing a switch where the panel light dimmer is and is no longer in use in case the fan does not come on or in case I anticipate some heavy traffic.

Any thoughts?  Thank you.

[jbcollier]

For a short run, 14g is fine for the battery feed to the relays.  Long run, use 12g.  Output from the relays to the lights/horn/what-have-you, is 14g.

You can feed a separate wire for each headlight but the is no need.  The stock wiring is fine.  You are just taking the load off the switches.  Using four-way billet connectors is fine.

Where is the rad fan switch located?  Lower, hot inlet?  Or, upper, cooler outlet?  If upper that is way too hot a switch.  If lower, it is still too hot but not as bad.  As well, what thermostat are you running?

[Pfreen]

I used a Cooper Bussman fuse/relay  module.  http://www1.cooperbussmann.com/pdf/36090f1a-b434-4910-98ec-1870f1f2519d.pdf

The part number I bought was Cooper Bussmann 15303-2-2-4,  It holds 5 relays and 10 fuses.  I mounted it vertically on the passenger side just to the right of the glove box.  I used aluminum threaded inserts in the wheel well to mount it.  I am very pleased with it.  I did not relay the headlights but I did do my AC, cooling fans, horn, and added accessories switched by ignition key.  I ran an extra  gauge (#6) wire to the alternator and to the battery from a 60 amp amp gauge.  I have an high output alternator to keep up with the extra cooling fans and the ac on my car.

[rjbaren]

My radiator fan switch is just above the lower hose.  I think it is in the stock position. 

I do not know what thermostat is in there as I did not rebuild the engine.